This invention relates to apparatus for preventing jackknife steering control loss on articulated vehicles as a result of jackknifing of the trailer. More particularly this invention relates to apparatus for limiting the articulation of a trailer by means of a stop element engaged in the forks of the fifth wheel.
Environmental, traffic and public protection considerations, as well as the operational economies of preventing hazardous material spills in highway traffic fatalities by crash avoidance have become increasingly important, particularly to business involved with long distance highway cargo transport. The reduction of steering control loss through prevention of over-articulation or xe2x80x9cjackknifingxe2x80x9d of the tractor/trailer combination is one means of achieving those objectives.
As a tractor/trailer combination unit begins to lose control due to over articulation, the driver experiences the increasingly difficult challenge of maintaining steering control until articulation of the trailer to the tractor about the king-pin reaches a critical angle. Commonly known as xe2x80x9cjackknifingxe2x80x9d, exceeding the xe2x80x9ccritical anglexe2x80x9d causes the driver to lose complete steering control until the unit comes to rest, often with catastrophic results.
It is known in the prior art to provide anti-jackknifing apparatus which relies on the insertion of a stop element between the forks of the fifth wheel so as to limit the permitted articulation between the trailer and the tractor.
U.S. Pat. No. 3,837,678 to Cicero described a horizontally plunging piston with an enlarged head which engaged between the forks of the fifth wheel. U.S. Pat. No. 3,972,542 to Dirks et al. described a tapered head portion of an abutment element which extended horizontally into the forks of the fifth wheel, a slideway for the element and remote control features. U.S. Pat. No. 4,068,860 to Meyers et al. was directed to a horizontally extending abutment element which included a head portion shaped to engage both the inner and outer portions of the forks of the fifth wheel.
U.S. Pat. No. 4,700,966 to Hawkins et al. introduced the concept of a pivoting lug mounted on a transverse shaft which was driven by a hydraulic cylinder. The cylinder and the transverse shaft were mounted in a rearwardly extending support frame which included a mounting bar which in turn was attached to a portion of the trailer frame.
One disadvantage of the Hawkins approach is that the apparatus must be relatively long in order to accommodate the cylinder and support frame. As a result, the apparatus must generally be mounted below the floor beams of the trailer. This in turn reduces the clearance between the apparatus and the top of the fifth wheel. Alternatively the Hawkins unit is installed by cutting out a portion of the floor beams and tucking the unit into the resulting space.
An object of this invention is to provide improved apparatus which selectively prevents jackknifing of the trailer by means of a pivoting lug mounted on a transverse shaft.
It is a further object of this invention to provide such apparatus which can be supplied as a retrofit device on an existing upper coupler plate of a trailer.
It is yet a further object of this invention to provide a more compact apparatus than has been offered in the prior art and which is capable of fitting between the floor beams of a trailer without the need to cut the beams.
It is another object of this invention to provide means for preventing contamination of the operative components of the apparatus from dirt and other debris.
It is another object of this invention to provide apparatus which may be easily taken apart for repair or replacement of its component parts.